Semiconductor package structure with heat sink and method preparing the same

ABSTRACT

The present disclosure provides a chip package structure having a heat sink and a method making the same. The method includes: bonding a chip to a top surface of a package substrate and forming a heat-conducting lead having an arc-shape and placed on the chip in a vertical direction, a first end of the heat-conducting lead is connected with a surface of the chip, and a second end is connected with a solder ball; forming a plastic package material layer that protects the chip and the heat-conducting lead; forming a heat-conducting adhesive layer on the surface of the plastic package material layer, where the heat-conducting adhesive layer is connected with the solder ball on the second end of the heat-conducting lead; and forming a heat dissipation layer on a surface of the heat-conducting adhesive layer. With the present disclosure, the heat dissipation efficiency of the chip is effectively improved.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of priority to U.S. patentapplication Ser. No. 17/195,389, entitled “SEMICONDUCTOR PACKAGESTRUCTURE WITH HEAT SINK AND METHOD PREPARING THE SAME”, filed Mar. 8,2021, which claims the priorities to Chinese Patent Application No.CN202010152816.1, entitled “Semiconductor Package Structure with HeatSink and Method Making the same”, filed with CNIPA on Mar. 6, 2020, andChinese Patent Application No. CN202020267066.8, entitled “SemiconductorPackage Structure with Heat Sink”, filed with CNIPA on Mar. 6, 2020, thecontents of all of which are incorporated herein by reference in theirentireties.

TECHNICAL FIELD

The present disclosure relates to the technical field of chip packaging,in particular, to a chip package structure having a heat sink and amethod making the same.

BACKGROUND

At the present time, rapid development of electronic informationtechnology and the continuous improvement of users' expectation, thefunctions of a single electronic device have become increasinglydiversified, at the same time a single electronic device's size has beencontinuously shringking. Therefore, in the internal structure of anelectronic equipment, densities of integrated circuit (IC) chips andfunctional components continue to increase and the critical dimensions(line/space widths, hole sizes, etc.) of these components continue todecrease, which have brought great challenges to the IC packagingindustry.

Ball Grid Array (BGA) as a semiconductor IC packaging technology iswidely used in the packaging market for shrinking ICs and has highdensity and multiple pins, has struggled to meet requirements forlighter, thinner, shorter, and smaller electronic products. However,since this chip packaging technique provides high-density electroniccircuits and electronic components, the heat generated during operationis also high. Moreover, in BGA type of chip packaging, the semiconductorIC chip is packaged with a layer of encapsulant, referred to as PlasticBall Grid Array (PBGA) package which has poor thermal conductivity.Therefore, the performance of the semiconductor chip is often affectedby poor heat dissipation efficiency. To improve the heat dissipationefficiency of the chip package, a heat sink (or heat slug, heat block)may be added to the PBGA package structure.

FIG. 1 shows a commonly used PBGA package structure with a heat sink.This package structure takes into account the heat dissipation problemand adds the heat sink to the package structure, a heat sink 14 extendsfrom a packaging substrate 11 to above a chip 12 through the supportconnection of several brackets. However, the problem with this structureis that the heat generated by the chip 12 needs to be conducted througha plastic packaging material layer 13 to reach the heat sink 14. Theplastic packaging material layer 13 is usually made of resin and haspoor thermal conductivity, resulting in a poor heat dissipation effectof the package structure. At the same time, this kind of packagestructure usually requires the mounting of the heat sink 14 after thechip 12 is bonded to the packaging substrate 11, and then the plasticpackaging of the plastic material layer 13, which is usually cured byliquid plastic material. Therefore, the plastic packaging material islikely to overflow on the surface of the heat sink 14 during the plasticpackaging process, resulting in a decrease in the heat dissipationeffect of the heat sink 14, and ultimately resulting in poor heatdissipation of the packaged device and decreased electrical performancecaused by poor heat dissipation.

SUMMARY

The embodiment of the present disclosure provides a method for making achip package structure having a heat sink.

The method includes the steps: providing a package substrate and a chip;bonding the chip to a top surface of the package substrate; forming aheat-conducting lead on the chip, wherein the heat-conducting leadcomprises an arc-shaped vertical wire having a first end and a secondend opposite to the first end, wherein the first end is connected with asurface of the chip through a wire bonding bump and the second end isconnected with a solder ball; disposing a plastic package material layerthat packages the chip and the heat-conducting lead, wherein a surfaceof the plastic package material layer exposes the solder ball on thesecond end of the heat-conducting lead; forming a heat-conductingadhesive layer on the surface of the plastic package material layer,wherein the heat-conducting adhesive layer is in contact with the solderball on the second end of the heat-conducting lead; and forming a heatdissipation layer on a surface of the heat-conducting adhesive layer.

In some examples, the heat-conducting adhesive layer is an electricallyconductive material layer.

In some examples, the heat dissipation layer includes an uneven surfacestructure.

In some examples, the heat dissipation layer comprises a metal bodylayer and a coating layer on the metal body layer.

In some examples, the chip is bonded to the top surface of the packagesubstrate by a bonding wire.

In some examples, the forming the heat-conducting lead having thearc-shaped vertical wire comprises: providing a bonding wire and acapillary, fixing a position of the bonding wire by the capillary,forming a solder ball at an end of the bonding wire, and soldering thesolder ball to a bonding pad on a surface of the chip; generating acrack by forcing the capillary to deform a part where the bonding wireis connected to the solder ball; lifting the capillary up by a presetdistance in a vertical direction, the preset distance defines a lengthof the heat-conducting lead, making the capillary reciprocate along anarc-shaped trajectory while keeping the capillary in the verticaldirection, to generate an internal stress in the bonding wire of thepreset distance; moving the capillary and the bonding wire in thevertical direction, breaking the bonding wire, forming the wire bondingbump, wherein the bonding wire under the capillary appears as anarc-shaped vertical line; forming the solder ball on the second end ofthe heat-conducting lead; soldering a top end of the bonding wire thatappears as the arc-shaped vertical wire to the wire bonding bump by thecapillary, wherein the bonding wire that appears as the arc-shapedvertical wire bends upward under an action of a soldering pressure; andforming the heat-conducting lead on the wire bonding bump by breakingthe bonding wire through the capillary.

In some examples, the generating of the crack by forcing the capillaryto deform the part where the bonding wire is connected to the solderball comprises: moving the capillary upward in the vertical direction,and moving the capillary to the right or left in a horizontal direction,thereby generating the crack.

In some examples, the forming of the heat-conducting lead on the wirebonding bump by breaking the bonding wire through the capillarycomprises: moving the capillary upward in the vertical direction, andpulling the bonding wire upward by the capillary until the bonding wireis broken, thereby forming the heat-conducting lead.

In some examples, the disposing the plastic package material layerfurther comprises: depositing the plastic package material on the topsurface of the package substrate, exposed surfaces of the chip, and theheat-conducting lead; and grinding and removing the plastic packagematerial to expose the solder ball on the second end of theheat-conducting lead, thereby forming the plastic package material layerfor plastic packaging the chip and the heat-conducting lead.

Another embodiment of the disclosure provides a chip package structurehaving a heat sink, comprising: a package substrate; a chip, bonded to atop surface of the package substrate; a plastic package material layer,disposed on an exposed part of the top surface of the package substrateand a top surface of the chip; a heat-conducting adhesive layer, locatedon a top surface of the plastic package material layer; a heatdissipation layer, located on a top surface of the heat-conductingadhesive layer; and a heat-conducting lead having an arc-shape andplaced on the chip in a vertical direction, wherein the heat-conductinglead includes a first end and a second end opposite to the first end,wherein the first end is connected with a surface of the chip through awire bonding bump, the second end is connected with a solder ball, andthe solder ball is connected with the heat-conducting adhesive layer.

In some examples, the chip is bonded to the top surface of the packagesubstrate by a bonding wire, and wherein the bonding wire and theheat-conducting lead are made of a same material.

In some examples, the heat-conducting adhesive layer is an electricallyconductive material layer.

In some examples, the heat dissipation layer includes an uneven surfacestructure.

In some examples, the heat dissipation layer comprises a metal bodylayer and a coating layer on the metal body layer.

As mentioned above, the chip package structure with the heat sink andthe method preparing the same of the present disclosure have thefollowing beneficial effects: by forming the heat dissipation layer onthe outer surface of the plastic package material layer, the heatdissipation surface area of the heat dissipation layer is increased, andthe heat-conducting lead transfers the heat from the chip to the heatdissipation layer of a larger area. Since the heat-conducting lead(metal material) has better thermal conductivity than the plasticpackage material layer (insulation material), the heat-conducting leadis set and combined with the heat dissipation layer of the large area,thereby effectively improving the heat dissipation efficiency of thechip. Besides, in the traditional wire bonding process, it is necessaryto cut off excess leads and part of the package substrate to form theheat-conducting lead. The present disclosure directly forms theheat-conducting lead of the arc-shaped vertical wire without removingthe bonding wire and part of the package substrate, which reducesprocess complexity, saves raw materials, and realizes the wire bondingprocess using existing machines and equipment, thereby effectivelyreducing manufacturing costs. Moreover, the heat-conducting lead isconnected with the heat-conducting adhesive layer through the solderball, which can further increase the contact area between theheat-conducting lead and the heat dissipation layer, and improve theheat dissipation efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic view of a cross-sectional structure of a chippackage structure in the related arts.

FIG. 2 shows a flow chart of a method for making a chip packagestructure with a heat sink according to the present disclosure.

FIGS. 3 to 11 show schematic cross-sectional views of the structuresobtained after each step of the method for preparing a chip packagestructure with a heat sink according to the present disclosure, whereinFIGS. 4 to 7 show the schematic views of the process for preparing theheat-conducting lead “A” inside the dashed oval in FIG. 3 , and FIG. 11shows a schematic cross-sectional view of the final chip packagestructure with the heat sink according to the present disclosure.

DESCRIPTION OF REFERENCE NUMERALS

-   -   11 Package substrate    -   12 Chip    -   13 Plastic package material layer    -   14 Heat sink    -   21 Package substrate    -   22 Chip    -   23 Heat-conducting lead    -   24 Solder ball    -   25 Plastic package material    -   26 Plastic package material layer    -   27 Heat-conducting adhesive layer    -   28 a Heat dissipation body layer    -   28 b Heat dissipation coating layer    -   29 Bonding wire    -   31 Bonding wire    -   32 Capillary    -   33 Bonding pad    -   34 Wire bonding bump    -   35 wire clamp    -   S1˜S4 Operations

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

The embodiments of the present disclosure will be described belowthrough exemplary embodiments. Those skilled in the art can easilyunderstand other advantages and effects of the present disclosureaccording to contents disclosed by the specification. The presentdisclosure can also be implemented or applied through other differentexemplary embodiments. Various modifications or changes can also be madeto all details in the specification based on different points of viewand applications without departing from the spirit of the presentdisclosure.

Referring to FIGS. 2-11 . It needs to be stated that the drawingsprovided in the following embodiments are just used for schematicallydescribing the basic concept of the present disclosure, thus onlyillustrating components related to the present disclosure and are notdrawn according to the numbers, shapes, and sizes of components duringactual implementation, the configuration, number and scale of eachcomponent during the actual implementation thereof may be freelychanged, and the component layout configuration thereof may be morecomplicated, and the “top” and “bottom” in this embodiment do not have astrictly limiting meaning but are only for the convenience ofdescription.

Embodiment 1

Referring to FIG. 2 , this embodiment provides a method for preparing achip package structure with a heat sink, by forming the heat dissipationlayer on the outer surface of the plastic package material layer, wherethe heat dissipation area of the heat dissipation layer is increased,and the heat-conducting lead transfers the heat from the chip to theheat dissipation layer of a large area. Since the heat-conducting lead(metal material) has better thermal conductivity than the plasticpackage material layer (insulation material), the heat-conducting leadis set and combined with the heat dissipation layer of the large area,thereby effectively improving the heat dissipation efficiency of thechip. Besides, in the traditional wire bonding process, it is necessaryto cut off excess leads and part of the package substrate to form theheat-conducting lead. This embodiment forms directly the heat-conductinglead which is an arc-shaped vertical wire. The process is simple and noadditional waste of materials occurs. The wire bonding process isrealized using existing machines and equipment, which effectivelyreduces the manufacturing cost. Moreover, the heat-conducting lead isconnected with the heat-conducting adhesive layer through the solderball, which can further increase the contact area with the heatdissipation layer and improve the heat dissipation efficiency.

FIGS. 3 to 11 show schematic views of the steps preparing the chippackage structure with the heat sink.

Referring to FIGS. 2 and 3 , operation S1 is performed. A packagesubstrate 21 is provided, a chip 22 is bonded to a top surface of thepackage substrate 21 to form a heat-conducting lead 23 of an arc-shapedvertical wire. The heat-conducting lead 23 includes a first end and asecond end opposite to the first end, the first end is connected withthe surface of the chip 22 through a wire bump 34, and the second end isconnected with a solder ball 24.

The materials of the package substrate 21 can be selected according todifferent needs. For example, it can be non-metallic materials such assilicon, glass, silicon oxide, ceramics, polymers, etc., or metalmaterials such as copper, or composite materials consisting of more thantwo elements. The shape of the package substrate 21 can be round,square, or another desired shape, and the surface area of the packagesubstrate 21 is required to be able to support the subsequent structureon top. In this embodiment, for subsequent package needs, the surfacearea of the package substrate 21 is larger than the contacting surfacearea of the chip 22. For example, the area of the package substrate 21is 1.1 to 2 times the contacting surface area of the chip 22.

As an example, the chip 22 may include various types of active orpassive components, the number of which may be one or more. In thisembodiment, the chip 22 is bonded to the package substrate 21 by wirebonding, that is, by a bonding wire 29. Two ends of the bonding wire 29are respectively connected to the package substrate 21 and the chip 22,and a bonding pad (not shown) may be provided on the surface of the chip22 to be connected to the bonding wire 29. The material of the bondingwire 29 is preferably gold, because a gold wire not only has goodelectrical conductivity and oxidation resistance, also has very goodductility and easy ball formation, thus helping to improve theperformance of the chip package structure. In other examples, the chip22 may be soldered on the package substrate 21 by die bonding, thereforethe bonding technique is not strictly limited in this embodiment.

As an example, the bonding wire 29 and the heat-conducting wire 23 aremade of the same material, such as the gold wire, so that theheat-conducting wire 23 and the bonding wire 29 may be formed in thesame process, which is beneficial to the simplification of thepreparation process. In other examples, the heat-conducting lead 23 mayconsist of other metallic materials with good thermal conductivity, suchas copper, aluminum, copper alloys, etc., so the heat-conducting leadmaterials are not strictly limited in this embodiment. The heatgenerated by the chip 22 can be quickly transferred through theheat-conducting lead 23 to the heat-conducting adhesive layer 27 (to beformed later shown in FIG. 10 ), and eventually radiated out into theambient through the heat dissipation layer formed on the heat-conductingadhesive layer 27. Compared to insulating materials, thermalconductivities of metal materials are generally better, as theheat-conducting lead 23 is used to increase the heat conduction path ofthe chip, so the heat dissipation efficiency of the chip 22 iseffectively improved. Moreover, the top end of the heat-conducting lead23 is connected to the solder ball 24, which further increases thecontact area between the heat-conducting lead 23 and the theheat-conducting adhesive layer 27 (see FIG. 10 ), and reaching to heatdissipation layer 28 a and 28 b, thus improving the heat dissipationefficiency. It should be noted here that the number of theheat-conducting lead 23 and the bonding wire 29 may be multiple, such as2 or more. The specific number can be set according to different productrequirements, and is not limited here.

FIGS. 4 to 7 show the schematic views of the process for preparing theheat-conducting lead 23 “A” in the dashed oval in FIG. 3 .

Referring to FIGS. 4 a-4 c and 5 a-5 c , a bonding wire 31, a capillary32, and a wire clamp 35 are provided, a position of the bonding wire 31is fixed by the capillary 32, a solder ball 24 is formed at an end ofthe bonding wire 31, and the solder ball 24 is soldered to a bonding pad33 on a surface of the chip 22.

The above-mentioned operations specifically include: the welding wire 31(as shown in 4 a) is clamped by the capillary 32 and the wire clamp 35;an end of the bonding wire 31 is melted by an electric spark to form asolder ball 24 (as shown in 4 b); the wire clamp 35 is loosed and thebonding wire 31 is moved upward so that the solder ball 24 is located atthe end of the capillary 32 (as shown in 4 c); the wire clamp 35 isclosed again (as shown in 5 a); the solder ball 24 is soldered on thesolder pad 33 by the capillary 32 (as shown in 5 b), the wire clamp 35is loosed, and the capillary 32 is moved upwards in the verticaldirection for a proper distance (as shown in 5 c), a wire bonding bump34 that is eutectic connected to the bonding pad 33 is formed on thebonding pad 33.

Referring to FIG. 6 a in FIG. 6 , the connecting part of the bondingwire 31 and the wire bonding bump 34 is deformed by the capillary 32 togenerate a crack.

The above operations specifically include: the capillary 32 is movedupward in the vertical direction, and the capillary 32 is moved to theright or left in the horizontal direction, so that the connecting partof the bonding wire 31 and the wire bonding bump 34 is deformed togenerate a crack.

Referring to FIG. 6 b in FIG. 6 , the capillary 32 is moved up a presetdistance in a vertical direction, the preset distance defines a lengthof the future heat-conducting lead, while keeping the capillary 32 inthe vertical direction, the capillary 32 reciprocates along anarc-shaped trajectory to make the bonding wire 31 of the preset distancegenerate internal stress and thus appear as an arc-shaped vertical line.

Referring to FIG. 6 c in FIG. 6 , the capillary 32 and the bonding wire31 are moved in the vertical direction to break the bonding wire 31,thereby forming the wire bonding bump 34, and the bonding wire 31 underthe capillary 32 appears as an arc-shaped vertical line. It should benoted that when the bonding wire 31 is pulled off, the wire clamp 35 iskept in a clamping state. A part of the arc of the shape of the weldingwire 31 under the capillary 32 in FIG. 6 c reduces length compared tothat in FIG. 6 b due to an upward pull force, but the shape of thebonding wire 31 below the capillary 32 in FIG. 6 c can be preciselycontrolled to be an arc-shaped vertical wire by presetting the upwardpull force, the parameters of which can be set according to the specificprocess, and there is no specific limit to these parameters here.

Referring to FIG. 6 d in FIG. 6 , the solder ball 24 is formed on thesecond end of the heat-conducting lead 23 at one end of the bonding wire31 that appears as the arc-shaped vertical wire. Specifically, the endof the bonding wire 31 is melted by an electric spark to form the solderball 24. It should be noted that when the solder ball 24 is formed, thewire clamp 35 is maintained in a clamping state.

Referring to FIG. 7 a in FIG. 7 , the top end of the bonding wire 31that appears as the arc-shaped vertical wire is soldered back to thewire bonding bump 34 by the capillary 32, and the bonding wire 31 thatappears as the arc-shaped vertical wire bends upward to form the shapeof the heat-conducting lead 23 in FIG. 3 . It should be noted thatduring the soldering process, the wire clamp 35 remains loosened.

Referring to FIGS. 7 b and 7 c in FIG. 7 , the heat-conducting lead 23is formed on the wire bonding bump 34 by breaking the bonding wire 31 atits bottom through the capillary 32.

The above operations specifically include: the wire clamp 35 remainsloosened, the capillary 32 is moved upward in the vertical direction,and the wire clamp 35 is clamped (as shown in 7 b). Then, the bondingwire 31 is pulled upward by the capillary 32 until the bonding wire 31is broken, thereby forming the heat-conducting lead 23.

Thus, a preparation cycle of the heat-conducting lead 23 is completed.In the traditional wire bonding process, it is necessary to cut offexcess leads and part of the package substrate to form theheat-conducting lead. The above method of this embodiment directly formsthe heat-conducting lead of the arc-shaped vertical wire withoutremoving the bonding wire and part of the package substrate, whichreduces process complexity, saves raw materials, and realizes the samewire bonding goal without using existing machines and equipment, therebyeffectively reducing manufacturing costs. Moreover, the heat-conductinglead 23 is connected with the heat-conducting adhesive layer 27 throughthe solder ball 24, which can further increase the contact area betweenthe heat-conducting lead 23 and the heat dissipation layer, thusimproving the heat dissipation efficiency.

Referring to FIGS. 2 and 9 , operation S2 is performed, a plasticpackage material layer 26 that packages the chip 22 and theheat-conducting lead 23 is formed, and a surface of the plastic packagematerial layer 26 exposes the solder ball 24 on the second end of theheat-conducting lead 23.

Referring to FIGS. 8-9 , as an example, the forming of the plasticpackage material layer 26 includes: forming a plastic package material25 on top surfaces of the package substrate 21, the chip 22, and theheat-conducting lead 23; and grinding and removing the plastic packagematerial 25 to expose the solder ball 24 on the second end of theheat-conducting lead 23, thereby forming the plastic package materiallayer 26 for plastic packaging the chip 22 and the heat-conducting lead23. (As shown in FIG. 9 )

As an example, the material of the plastic package material layer 26 mayinclude, but is not limited to, one or more of polyimide, siliconerubber, and epoxy resin. The process of forming the plastic packagematerial layer 26 may include, but is not limited to, one or more of aninkjet process, a dispensing process, a compression molding process, atransfer molding process, a liquid sealing process, a vacuum laminationprocess, or a spin coating process.

Referring to FIGS. 2 and 10 , operation S3 is performed, aheat-conducting adhesive layer 27 is formed on the surface of theplastic package material layer 26, the heat-conducting adhesive layer 27is connected with the solder ball 24 on the second end of theheat-conducting lead 23.

As an example, the heat-conducting adhesive layer 27 may be aninsulating material layer, such as a silicone rubber layer. However, inthis embodiment, the heat-conducting adhesive layer 27 is preferably amaterial layer with a conductive function, such as a conductive silveradhesive layer, so that the heat dissipation layer 28 is groundedthrough the heat-conducting adhesive layer 27, and the heat dissipationlayer 28 can play the role of electromagnetic shielding while realizingthe heat dissipation function, thereby improving the performance of thechip package device. The process of forming the heat-conducting adhesivelayer 27 may include, but is not limited to, one or more of an inkjetprocess, a dispensing process, a compression molding process, a transfermolding process, a liquid sealing process, a vacuum lamination process,or a spin coating process. In this embodiment, the inkjet process ordispensing process is preferred, so that it is easier to form theheat-conducting adhesive layer 27 with a non-flat structure on thesurface, so there are more choices in the subsequent process of formingthe heat dissipation layer 28 with a non-flat surface structure. Forexample, the heat dissipation layer having a metal body layer 28 a and acoating layer 28 b on the metal body layer 28 a can be formed byphysical vapor deposition or electroplating. Because the heat-conductingadhesive layer 27 has a non-flat surface structure, the formed heatdissipation body layer 28 a naturally has the non-flat surfacestructure, so that the heat dissipation body layer 28 a has a largerheat dissipation surface area, which can avoid deformation caused bythermal expansion and/or adverse effects caused by stress. At the sametime, the heat-conducting adhesive layer 27 and the heat dissipationlayer 28 a can be more closely attached, so that the heat of the chip 22can be transferred to the heat dissipation layer 28 faster through theheat-conducting adhesive layer 27 and finally emitted to the externalenvironment.

Referring to FIGS. 2 and 11 , operation S4 is performed, a heatdissipation layer 28 is formed on the top surface of the heat-conductingadhesive layer 27.

As an example, the heat dissipation layer 28 may include any materialswith good heat dissipation characteristics. In this embodiment, as anexample, the heat dissipation layer includes a metal body layer 28 a anda coating layer 28 b on the metal body layer 28 a as shown in FIG. 11 .The metal body layer 28 a may be a copper layer, an aluminum layer, astainless steel layer, a copper alloy layer, or a composite layer ofmultiple metal layers. The coating layer may be a nickel layer, achromium layer, or other coatings with good rust and corrosionresistance. The coating layer is used to protect the metal body layer 28a to prevent the metal body layer 28 a from being oxidized and/orcorroded, which causes the heat dissipation performance to decrease, andto ensure the heat dissipation performance of the heat dissipation bodylayer 28 a. The surface area of the heat dissipation layer 28 is usuallynot less than the surface area of the plastic package material layer 26,that is, the heat dissipation layer 28 a and 28 b covers the plasticpackage material layer 26, and the edge of the heat dissipation layer 28may be bent downward to wrap a part of the sidewalls of the plasticpackage material layer 26. This arrangement increases the heatdissipation area of the heat dissipation layer 28, increases the heatdissipation path of the chip package structure, and makes the connectionbetween the heat dissipation layer 28 and the plastic package materiallayer 26 more stable, which improves the performance of the chip packagestructure.

In another example, the heat dissipation layer 28 includes a graphenelayer. Graphene not only conducts electricity, but also has good heatdissipation properties, as well as good oxidation and corrosionresistance. Using graphene as the heat dissipation layer 28 can reducethe thickness of the heat dissipation layer 28, which is beneficial tothe further miniaturization of the chip package device. If the heatdissipation layer 28 is a graphene layer, the heat dissipation layer 28may be formed by a transfer molding method.

As an example, the heat dissipation layer 28 has a non-flat surfacestructure, that is, the surface of the heat dissipation layer 28 is notflat, for example, it may be a bumpy structure, or a corrugatedstructure, or any other irregular shape, which is not strictly limitedin this embodiment. The surface of the heat dissipation layer 28 is setto be non-flat, on the one hand, the surface area of the heatdissipation layer 28 can be increased to make a larger heat dissipationarea, on the other hand, the non-flat surface structure is provided toavoid expansion, deformation, and stress of the heat dissipation layer28 when heated to ensure the performance of the chip package structure.

Embodiment 2

This embodiment provides a chip package structure with a heat sink. Thepackage structure may be prepared by the method described in Embodiment1, but is not limited to the method described in Embodiment 1, as longas the package structure can be formed. Referring to Embodiment 1 forthe beneficial effects that the structure can achieve, which will not bedescribed in detail below.

Referring to FIG. 11 , the package structure includes: a packagesubstrate 21; a chip 22, bonded to a top surface of the packagesubstrate; a plastic package material layer 26, located on top surfacesof the package substrate 21 and the chip 22, and plastic packaging thechip 22; a heat-conducting adhesive layer 27, located on a top surfaceof the plastic package material layer 26; a heat dissipation layerhaving two parts 28 a as the body part and 28 b as the coating part,located on a top surface of the heat-conducting adhesive layer 27; and aheat-conducting lead 23 of an arc-shaped vertical wire, theheat-conducting lead 23 includes a first end and a second end oppositeto the first end, the first end is connected with a surface of the chip22 through a wire bonding bump 34, the second end is connected with asolder ball 24, and the solder ball 24 is connected with theheat-conducting adhesive layer 27.

As an example, the chip 22 is bonded to the top surface of the packagesubstrate 21 by a bonding wire 29, and the bonding wire 29 and theheat-conducting lead 23 are made of the same material.

As an example, the heat-conducting adhesive layer 27 is a conductivematerial layer, for example, a conductive silver adhesive layer.

As an example, the heat dissipation layer 28 includes an uneven surfacestructure.

As an example, the heat dissipation layer 28 includes a metal body layerand a coating layer on the metal body layer.

In summary, the present disclosure provides a method for preparing achip package structure with a heat sink, by forming the heat dissipationlayer on the outer surface of the plastic package material layer, theheat dissipation area of the heat dissipation layer is increased, andthe heat-conducting lead transfers the heat from the chip to the heatdissipation layer of a large area. Since the heat-conducting lead (metalmaterial) has better thermal conductivity than the plastic packagematerial layer (insulation material), the heat-conducting lead is setand combined with the heat dissipation layer of the large area, therebyeffectively improving the heat dissipation efficiency of the chip.Besides, in the traditional wire bonding process, it is necessary to cutoff excess leads and part of the package substrate to form theheat-conducting lead. The present disclosure directly forms theheat-conducting lead of the arc-shaped vertical wire without removingthe bonding wire and part of the package substrate, which reducesprocess complexity, saves raw materials, and realizes the wire bondingprocess using existing machines and equipment, thereby effectivelyreducing manufacturing costs. Moreover, the heat-conducting lead isconnected with the heat-conducting adhesive layer through the solderball, which can further increase the contact area between theheat-conducting lead and the heat dissipation layer, and improve theheat dissipation efficiency. Therefore, the present disclosureeffectively overcomes various shortcomings in the existing technologyand has high industrial utilization value.

While particular elements, embodiments, and applications of the presentinvention have been shown and described, it is understood that theinvention is not limited thereto because modifications may be made bythose skilled in the art, particularly in light of the foregoingteaching. It is therefore contemplated by the appended claims to coversuch modifications and incorporate those features which come within thespirit and scope of the invention.

The invention claimed is:
 1. A chip package structure having a heatsink, comprising: a package substrate; a chip, bonded to a top surfaceof the package substrate; a plastic package material layer, disposed onan exposed part of the top surface of the package substrate and a topsurface of the chip; a heat-conducting adhesive layer, located on a topsurface of the plastic package material layer; a heat dissipation layer,located on a top surface of the heat-conducting adhesive layer; and aheat-conducting lead having an arc-shape and placed on the chip in avertical direction, wherein the heat-conducting lead includes a firstend and a second end opposite to the first end, wherein the first end isconnected with a surface of the chip through a wire bonding bump, thesecond end is connected with a solder ball, and the solder ball isconnected with the heat-conducting adhesive layer.
 2. The chip packagestructure having the heat sink according to claim 1, wherein the chip isbonded to the top surface of the package substrate by a bonding wire,and wherein the bonding wire and the heat-conducting lead are made of asame material.
 3. The chip package structure having the heat sinkaccording to claim 1, wherein the heat-conducting adhesive layer is anelectrically conductive material layer.
 4. The chip package structurehaving the heat sink according to claim 1, wherein the heat dissipationlayer includes an uneven surface structure.
 5. The chip packagestructure having the heat sink according to claim 1, wherein the heatdissipation layer comprises a metal body layer and a coating layer onthe metal body layer.